Gear drive and actuator arrangement

ABSTRACT

A number of variations may include a gear drive comprising: a housing; a first ring gear; a shaft supported in the housing, wherein the shaft has a central axis of rotation; a second ring gear, wherein the second ring gear is coaxial with the shaft and operably connected and rotatable with the shaft; at least one intermediate gear, wherein the at least one intermediate gear includes a first end and a second end, wherein the first end is operably engaged with the first ring gear and the second end is operably engaged with the second ring gear; and a bias spring, wherein the bias spring comprises a first end, a second end, and a plurality of coils, and wherein the first end is stationary in the housing.

TECHNICAL FIELD

The field to which the disclosure generally relates to includes gearsand actuators.

BACKGROUND

An engine system may include one or more gears and actuators.

SUMMARY OF ILLUSTRATIVE VARIATIONS

A number of variations may include a gear drive comprising: a housing; afirst ring gear; a shaft supported in the housing, wherein the shaft hasa central axis of rotation; a second ring gear, wherein the second ringgear is coaxial with the shaft and operably connected and rotatable withthe shaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end is operably engaged with the first ring gear and the secondend is operably engaged with the second ring gear; and a bias spring,wherein the bias spring comprises a first end, a second end, and aplurality of coils, and wherein the first end is stationary in thehousing.

A number of variations may include a gear drive and actuator comprising:a housing; an electrical device supported in the housing constructed andarranged to provide a rotational force in response to an electricalcontrol signal; a first shaft, wherein the first shaft is constructedand arranged to receive the rotational force from the electrical device;a central gear with a plurality of gear teeth, wherein the central gearis attached to the rotatable shaft and is rotatable with the shaft; afirst ring gear with a plurality of gear teeth; a second shaft supportedin the housing which has a central axis of rotation; a second ring gearwith a plurality of gear teeth, wherein the second ring gear is coaxialwith the second shaft and operably connected and rotatable with thesecond shaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end engages and contacts the central gear and the first ring gear,and wherein the second end engages and contacts the second ring gear; anintermediate gear plate, wherein the intermediate gear plate is coaxialwith the second ring gear and the second shaft; and a bias spring,wherein the bias spring includes a first end, a second end, and aplurality of coils, and wherein the first end is stationary in thehousing.

Other illustrative variations within the scope of the invention willbecome apparent from the detailed description provided hereinafter. Itshould be understood that the detailed description and specificexamples, while disclosing variations within the scope of the invention,are intended for purposes of illustration only and are not intended tolimit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Select examples of variations within the scope of the invention willbecome more fully understood from the detailed description and theaccompanying drawings, wherein:

FIG. 1 illustrates a schematic of an engine system according to a numberof variations.

FIG. 2 illustrates a perspective view of a gear drive and actuatorassembly according to a number of variations.

FIG. 3 illustrates a perspective view of a gear drive and actuatorassembly with portions removed according to a number of variations.

FIG. 4 illustrates a perspective view of internal components of a geardrive and actuator assembly according to a number of variations.

FIG. 5 illustrates an end view of a gear drive and actuator assemblyaccording to a number of variations.

FIG. 6 illustrates a section view taken along line A-A of the gear driveand actuator assembly of FIG. 5 according to a number of variations.

FIG. 7 illustrates a section view taken along line B-B of the gear driveand actuator assembly of FIG. 5 according to a number of variations.

FIG. 8 illustrates an enlarged view of section C taken from the geardrive and actuator assembly of FIG. 7 according to a number ofvariations.

FIG. 9 illustrates a perspective view of a gear arrangement according toa number of variations.

FIG. 10 illustrates a top view of a gear arrangement according to anumber of variations.

FIG. 11 illustrates a section view taken along line D-D of the geararrangement illustrated in FIG. 10 with portions removed according to anumber of variations.

FIG. 12 illustrates a partial exploded view of a gear drive and actuatorassembly according to a number of variations.

FIG. 13 illustrates a perspective view of a gear according to a numberof variations.

FIG. 14 illustrates a perspective view of a gear according to a numberof variations.

FIG. 15 illustrates a perspective view of a gear drive and actuatorassembly according to a number of variations.

FIG. 16 illustrates an end view of a gear drive and actuator assemblyaccording to a number of variations.

FIG. 17 illustrates a section view taken along line E-E of the geardrive and actuator assembly of FIG. 16 according to a number ofvariations.

FIG. 18 illustrates a perspective view of an actuator and gear driveaccording to a number of variations.

FIG. 19 illustrates a perspective view of an actuator and gear drivewith portions removed according to a number of variations.

DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS

The following description of the variations is merely illustrative innature and is in no way intended to limit the scope of the invention,its application, or uses.

Any number of devices including, but not limited to, turbochargers andexhaust gas recirculation (EGR) valves, may use a device which maycontrol the function and/or the performance of the device. In oneillustration, one or more pneumatic and/or electric actuators may beused to provide positional control of various mechanisms on aturbocharger to adjust and maintain pressure which may be within anintake manifold of an engine. Controlling the intake manifold pressuremay provide optimum performance of the turbocharger and may alsomaintain legislated vehicle emissions requirements.

FIG. 1 illustrates a number of variations. In one variation, an internalcombustion engine 9 may include an electronic control unit (ECU) 1, anactuator controller 2, an actuator 3, a turbocharger 4, and aturbocharger control mechanism 5. In a number of variations, the ECU 1may include a main controller and/or a control subsystem which mayinclude one or more controllers (not separately illustrated) incommunication with the components of the system for receiving andprocessing sensor input and transmitting output signals. Thecontroller(s) may include one or more suitable processors and memorydevices (not separately illustrated). The memory may be configured toprovide storage of data and instructions that provide at least some ofthe functionality of the engine system and that may be executed by theprocessor(s). At least portions of the method may be enabled by one ormore computer programs and various engine system data or instructions,operating condition data stored in memory as look-up tables, formulas,algorithms, maps, models, or the like. The control subsystem may controlthe parameters of the system by receiving input signals from thesensors, executing instructions or algorithms in light of sensor inputsignals, and transmitting suitable output signals to the variousactuators, and/or components. As used herein, the term “model” mayinclude any construct that represents something using variables, such asa look up table, map, formula, algorithm and/or the like. Models may beapplication specific and particular to the exact design and performancespecifications of any given engine system. A controller system maincontroller and/or a control subsystem may include one or morecontrollers (not separately illustrated) in communication with thecomponents of the system for receiving and processing sensor input andtransmitting output signals in a method consistent with the illustratedvariations described herein.

In a number of variations, the ECU 1 may be operatively connected to theactuator controller 2 by a first wire harness 6 which may comprise aplurality of conductors and connectors. In a number of variations, theactuator controller 2 may also be connected to the actuator 3 by asecond wire harness 7 which may comprise a plurality of conductors andconnectors. In a number of variations, the actuator controller 2 may bea separate component from the actuator 3, a variation of which isillustrated in FIG. 1. In another variation, the actuator controller 2may be integrated within the actuator 3. In any number of variations,the internal combustion engine 9 may include a system which may use theturbocharger 4 and the actuator 3 to control the boost pressure withinthe intake manifold 8.

In a number of variations, the ECU 1 may send an electrical positioninput signal to the actuator controller 2 which may indicate a desiredposition of the actuator 3. In a number of variations, the actuatorcontroller 2 may then provide an electrical control signal to theactuator 3 which may move the actuator 3 to the desired position. Theactuator 3 may then move the control mechanism 5 of the turbocharger 4to a desired position which may achieve a required pressure within theintake manifold 8 of the internal combustion engine 9. In a number ofvariations, the actuator 3 may also include a means of sensing itsposition and may feedback an electrical position output signal to theactuator controller 2. In a number of variations, a “closed loop”control scheme may be used to maintain a desired actuator position bycomparing the feedback electrical output signal value to a desiredvalue. The control signal to the actuator 3 may then be adjusted tomaintain the position and resulting boost pressure.

In a number of variations, the actuator 3 may use an electrical deviceincluding, but not limited to, a Direct Current (D.C.) motor, forproviding a means of actuation. Any number of D.C. motors may be used.In one variation, the D.C. motor may use brushes for commutating itsrotating member. In another variation, the D.C. motor may be brushlessincluding, but not limited to, a stepper motor. The actuator output maybe rotary or linear motion and a gear system may be used to increase thetorque or linear force.

In a number of variations, a gear arrangement 116, which may be referredto as planetary gear arrangement, may provide optimized performancerequirements and may allow for a compact actuator. In a number ofvariations, the planetary gear arrangement 116 may comprise a pluralityof gears 108, 117, 128, 129 including, but not limited to, four to eightgears. The planetary gear set 116 may be constructed and arranged sothat the gears 108, 117, 128, 129 may be optimally aligned. This mayprevent misalignment of the gears 108, 117, 128, 129 which may causebinding and wear that may reduce torque, durability, and reliability. Ina number of variations, the gears 108, 117, 128, 129 may also beconstructed and arranged to provide efficient manufacturing processesfor components and product assembly.

FIGS. 2-9 illustrate a number of variations including a gear drive andactuator assembly 100. It is noted that the gear drive and actuatorassembly 100 discussed hereafter provides a rotary output forillustrative purposes, however, it is within the scope of the inventionto have a gear drive actuator assembly 100 which may provide linearmovement by using a lead screw or another motion conversion mechanism.

In a number of variations, the gear drive and actuator assembly 100 mayinclude a housing 101. In one variation, the housing 101 may comprise afirst housing portion 102 and a second housing portion 103. In anothervariation, one housing portion may be used or more than two housingportions may be used depending on the internal component design andmanufacturing process. The housing 101 may comprise any number ofsuitable materials including, but not limited to, aluminum, plastic, orcast iron. In a number of variations, an electrical device 106 may belocated in the first housing portion 102. In one variation, theelectrical device 106 in the gear drive and actuator assembly 100 may bea brushless D.C. motor, variations of which are illustrated in FIGS. 3and 4. In another variation, the electrical device 106 may be a brushD.C. motor, a stepper motor, or any number of rotary devices. Theelectrical device 106 may be secured in the first housing portion 102 inany number of variations including, but not limited to, one or moremechanical fasteners. In one variation, the one or more mechanicalfasteners may include, but are not limited to, screws or rivets.

In a number of variations, the gear drive and actuator assembly 100 mayinclude a first shaft 107 and central gear 108, a variation of which isillustrated in FIG. 4, which may be rotated by the electrical device 106in response to an electrical control signal which may be sent from anECU 109, a variation of which is illustrated in FIG. 2. The first shaft107 may be supported and guided by a first bearing 115 which may besecured in the first housing portion 102, a variation of which isillustrated in FIG. 6, in any number of variations including, but notlimited to, press fitting, staking, or any other suitable means. In anumber of variations, the central gear 108 may have a diameter d5 and aplurality of gear teeth 133 which may be located on the diameter d5 ofthe central gear 108, a variation of which is illustrated in FIG. 7.

In a number of variations, the gear drive and actuator assembly 100 mayalso include a cover 104 and an electrical connector 105 which may beattached and sealed to the cover 104, variations of which areillustrated in FIGS. 2, 5, and 6. In one variation, the electricalconnector 105 may be attached and sealed to the cover 104 by a pluralityof screws 112 and a seal 111, variations of which are illustrated inFIGS. 5 and 6. In a number of variations, the electrical connector 105may include a plurality of terminals 110 which may provide electricalconnections to the electrical device 106 and may also provide thedesired electrical control to the gear drive and actuator assembly 100.In one variation, the number of terminals 110 may vary between four andeight and may depend on whether the primary actuator control may beinternal to the gear drive and actuator assembly 100 or in the ECU 109.In a number of variations, the electrical connector 105 may be moldedfrom a type of plastic or other suitable material. In a number ofvariations, the electrical connector 105 and the cover 104 may be madeas a single component or the electrical connector 105 and the cover 104may be separate components, a variation of which is illustrated in FIG.6. The cover 104 may be secured to the first housing portion 102 in anynumber of variations including, but not limited to, one or more screws113, a crimp ring, or any other suitable means. In one variation, a seal114 may seal the cover 104 and the first housing portion 102 from theexternal environment.

In a number of variations, a gear drive arrangement 116 may be locatedwithin the first housing portion 102 and the second housing portion 103.In a number of variations, a first ring gear 117 may be located in thecounter bore 118 of the first housing portion 102, a variation of whichis illustrated in FIG. 6. The first ring gear 117 may be secured to thecounter bore 118 in any number of variations including, but not limitedto, press fitting, staking, or any other suitable means. In a number ofvariations, the first ring gear 117 may be stationary and may notrotate. The first ring gear 117 may have a first diameter d1 and aplurality of gear teeth 134 located on the first diameter d1, variationsof which are illustrated in FIGS. 7-8. In one variation, the first ringgear 117 may also include one or more locating/anti-rotation features120, a variation of which is illustrated in FIG. 7, which may engagewith the first housing portion 102 and which may locate the first ringgear 117 and may prevent rotation thereof.

In a number of variations, an output shaft 121 may be located in thesecond housing portion 103 and may be supported for rotation by a firstbushing 122 and a second bearing 123, a variation of which isillustrated in FIG. 6. In a number of variations, the output shaft 121may have a first end 124, a second end 125, and a central axis ofrotation 126. The first shaft 107 may also have the same central axis ofrotation 126 as the output shaft 121. In a number of variations, thefirst end 124 may be fitted with a lever 127 which may be attached to adevice including, but not limited to, a turbocharger, requiring controlof a parameter. The controlled parameter may include, but is not limitedto, the closure of turbine vanes, the movement of a waste gate valve, orany other controlled parameter. In a number of variations, a second ringgear 128 may be adjacent the second end 125 of output shaft 121. Thesecond ring gear 128 may be operatively attached to the output shaft 121so that it may be coaxial and rotatable with the output shaft 121. In anumber of variations, the second ring gear 128 may have a seconddiameter d2 and a plurality of gear teeth 135 located on a seconddiameter d2, variations of which are illustrated in FIGS. 7 and 8. Thesecond ring gear 128 may comprise any number of materials including, butnot limited to, metal or plastic. The second ring gear 128 may besecured to the output shaft 121 by any number of variations including,but not limited to, press fitting or over molding.

In a number of variations, at least one intermediate gear 129 may belocated between the first ring gear 117 and the second ring gear 128, avariation of which is illustrated in FIG. 7. The intermediate gear 129may have a first end 130 which may have a third diameter d3 and aplurality of gear teeth 136 which may be located on the third diameterd3. The intermediate gear 129 may also have a second end 131 which mayhave a fourth diameter d4 and a plurality of gear teeth 137 which may belocated on the fourth diameter d4, a variation of which is illustratedin FIG. 9. In a number of variations, the number of intermediate gearsused in a gear drive arrangement 116 may be determined by the operatingloads, durability requirements, and/or other parameters. It is notedthat the gear drive arrangement described herein illustrates a variationwhich includes three intermediate gears, however, it is within the scopeof the invention to use various number of gears including, but notlimited to one, two, or more than three intermediate gears to achievedesired requirements.

Referring to FIGS. 6 and 9-11, the intermediate gear 129 may be locatedand supported by an intermediate gear plate 132 which may be coaxialwith the output shaft 121, the second ring gear 128, and the centralaxis of rotation 126, which may provide precise alignment of the gears108, 117, 128, 129 which may prevent binding, wear, misassembly, andother issues. In a number of variations, the intermediate gear plate 132may be fitted with an engagement feature including, but not limited to,a second bushing 138, variations of which are illustrated in FIGS. 10and 11, which may engage the second end 125 of the output shaft 121 andmay provide alignment. In a number of variations, the second bushing 138may also provide a bearing surface which may allow for independentrotation of the intermediate gear plate 132 about the output shaft 121.The second bushing 138 may be secured to the intermediate gear plate 132in any number of variations including, but not limited to, press fittingor staking. A pin 139 may be attached to the intermediate gear plate 132and may be used for locating and supporting the intermediate gear 129.In a number of variations, a clearance 119 between the outside diameterof the pin 139 and the intermediate gear 129, a variation of which isillustrated in FIG. 11, may allow for rotation of the intermediate gear129 about the pin 139. In a number of variations, the locating andengagement features provided by the intermediate gear plate 132 and thesecond bushing 138 may provide precise alignment and movement of thegears 108, 117, 128, 129 within the gear arrangement 116.

Referring to FIGS. 5, 6, and 12, in a number of variations, a first ringgear 117, which may be located in the first housing portion 102, may becoaxial and aligned with the second ring gear 128 and the output shaft121, which may be located in the second housing portion 103, so that thegear arrangement 116 may perform optimally. It may also be desirable tohave the first housing portion 102 and the second housing portion 103“clocked” to a predetermined point on each housing portion 102, 103. Ina number of variations, a first cylindrical feature 140 and a firstsurface 141 may be provided in the first housing portion 102, avariation of which is illustrated in FIG. 6. In a number of variations,the first cylindrical feature 140 may be coaxial with the counter bore118 and the central axis of rotation 126. In a number of variations, thefirst surface 141 may be perpendicular to the first cylindrical feature140. In a number of variations, a second cylindrical feature 142 and asecond surface 143 may be provided in the second housing portion 103.The second cylindrical feature 142 may be coaxial with the central axisof rotation 126. The second surface 143 may be perpendicular to thesecond cylindrical feature 142. In a number of variations, the first andthe second cylindrical features 140, 142 and the first and the secondsurfaces 141, 143 may be provided to desired fit and alignmenttolerances in any number of suitable variations including, but notlimited to, machining or die casting. In one variation, a clockingfeature may also be provided by locating a pin 144 in the second housingportion 103 so that the pin 144 may engage a mating hole 145 which maybe located in the first housing portion 102, a variation of which isillustrated in FIG. 12. In another variation, the pin may be located onthe first housing portion 102 and the mating hole may be located on thesecond housing portion 103.

In a number of variations, the first housing portion 102 and the secondhousing portion 103 may be assembled by aligning and engaging of thefirst cylindrical feature 140 on the first housing portion 102 and thesecond cylindrical feature 142 on the second housing portion 103 andthen rotating the first housing portion 102 and the second housingportion 103 until the pin 144 on the second housing portion aligns withand engages the mating hole 145 on the first housing portion 102. In anumber of variations, the axial engagement of the first and the secondcylindrical features 140, 142 may continue until the first and thesecond surfaces 141, 143 may be in contact. The first housing portion102 and the second housing portion 103 may be secured together in anynumber of variations including, but not limited to, one or more threadedfasteners 146 or a crimp ring. In a number of variations, the firsthousing portion 102 and the second housing portion 103 may be sealedfrom the environment in any number of variations including, but notlimited to, an elastomer seal 147 or a gasket. The use of a firsthousing portion 102 and a second housing portion 103 is discussed abovefor illustrative purposes, however, it is within the scoop of theinvention to use a single housing which may also minimize alignmentissues.

Referring to FIGS. 2 and 6-11, in a number of variations, the gear drivearrangement 116 may operate so that the first end 130 and the gear teeth136 located on the diameter d3 of the intermediate gear 129, mayoperably engage with the gear teeth 133 located on the diameter d5 ofthe central gear 108. In a number of variations, the first end 130 andthe gear teeth 136 on the diameter d3 of the intermediate gear 129 mayalso operably engage the gear teeth 134 located on the first diameter d1of the first ring gear 117. In a number of variations, the second end131 and the gear teeth 137 on the second diameter d4 of the intermediategear 129 may operably engage with the gear teeth 135 which may belocated on the second diameter d2 of the second ring gear 128.

In a number of variations, the ECU 109 may provide an electrical controlsignal to the electrical device 106 which may cause the first shaft 107and the central gear 108 to rotate in a direction that may be determinedby the control signal. The engagement of the gear teeth 133 on thecentral gear 108 and the gear teeth 136 on the first end of theintermediate gear 129 may cause the intermediated gear 129 to rotate. Ina number of variations, the gear teeth 136 on the first end 130 of theintermediate gear 129 may also be engaged with the gear teeth 134 on thefirst ring gear 117. The first ring gear 117 may be fixed to the firsthousing portion 102 so that the engagement of the gear the teeth 134 onthe first ring gear 117, and the rotation of the intermediated gear 129,may cause the intermediate gear 129 to move in a direction along thegear teeth 134 of the first ring gear 117. In a number of variations,the movement of the intermediate gear 129 along the gear teeth 134 offirst ring gear 117 may also cause the intermediate gear plate 132 torotate about the central axis of rotation 126 of the output shaft 121.The gear teeth 137 on the diameter d4 of the second end 131 of theintermediate gear 129 may also be engaged with the gear teeth 135located on the second ring gear 128. The second ring gear 128 may rotateabout the central axis of rotation 126 of the output shaft 121. In anumber of variations, the engagement of the gear teeth and rotation ofthe intermediate gear 129 may cause the second ring gear 128 to rotatein a first direction 148 or a second direction 149, a variation of whichis illustrated in FIG. 2, and the second ring gear 128 may be attachedto the output shaft 121 so that the output shaft 121 may rotate in thesame direction 148, 149 as the second ring gear 128.

In a number of variations, the direction of the rotation of the gear maybe determined, in part, by the electrical control signal provided by theECU 109 to the electrical control device 106. In one variation, the ECU109 may provide a first electrical control signal with a firstelectrical polarity that may move the gears 108, 117, 128, 129 of thegear drive arrangement 116, in directions which may cause the outputshaft 121 to rotate in the first direction 148. The ECU 109 may alsoprovide a second electrical control signal with a second electricalpolarity that may move the gears 108, 117, 128, 129 of the gear drivearrangement 116, in directions that may cause the output shaft 121 torotate in a second direction 149. In a number of variations, thedirectional rotation of the output shaft 121 may provide control ofmechanisms as previously described herein.

In a number of variations, a gear diameter dx, such as d1, may be adiameter at which the gear teeth of at least two gears contact eachother. The contact point between the at least two gears may, in part,determine the force and resulting stress applied to the gear teeth ofgears 108, 117, 128, 129. In one illustration, a gear drive arrangement116 may include a central gear 108 which may have a diameter d5 ofapproximately 10 mm and sixteen gear teeth 133. The diameter d5 may bethe contact diameter d5 for the gear teeth 133 of the central gear 108and the gear teeth 136 at the first end 130 of the intermediate gear129. The intermediate gear 129 may have twenty-one gear teeth 136. Thetwenty-one gear teeth 136 of the intermediate gear 129 may be located ona diameter d3 equal to approximately 14.03 mm at the first end 130 ofthe intermediate gear 129. The diameter d3 may act as the contactdiameter for the gear teeth 136 of the intermediate gear 129 and thegear teeth 134 of the first ring gear 117. The first ring gear 117 mayhave fifty-three gear teeth 134.

The intermediate gear 129 may also have a diameter d4 which may beapproximately 13.60 mm and may include twenty-one gear teeth 137 at thesecond end 131 of the intermediate gear 129. In this illustration, thediameter d4 may be the contact diameter for the gear teeth 137 of theintermediate gear 129 and the gear teeth 135 of the second ring gear128. The second ring 128 may have fifty-six gear teeth 135.

The variations provided for a gear drive arrangement 116 may also beused to determine other parameters including, but not limited to, themechanical advantage of the gear drive arrangement 116. The mechanicaladvantage may be the multiplying factor for torque applied to the firstrotating shaft 107 and measured at the output shaft 121. The mechanicaladvantage may be calculated using the number of gear teeth on thecentral gear 108, the first ring gear 117, and the second ring gear 128.In one variation, the gear drive arrangement 116 described herein, mayinclude a mechanical advantage that may be approximately 80.5:1. Thismay mean that the torque measured at the output shaft 121 may be 80.5times the input torque applied to the first shaft 107.

The number of gear teeth 136, 137 on the first end 130 and the secondend 131 of the intermediate gear 129 in the above illustration were eachtwenty-one and the contact diameters d3, d4 between the intermediategear 129 and the first and second ring gears 117, 128 were different.This may be achieved by adjusting parameters which may include, but arenot limited to, the contact point of the gears, the number of gearteeth, or any other suitable parameter. This may allow for the use of asingle number of gear teeth and a common gear tooth profile along theentire length of the intermediate gear 129 between the first and secondends 130 and 131 of the intermediate gear 129. This may also allow forthe use of less complex component tooling and manufacturing processes.

Referring to FIGS. 13 and 14, in another variation, the gear drivearrangement 116 may include an intermediate gear design which mayinclude a stepped feature. The gear drive components may be similar tothe ones previously described, therefore, only the intermediate geardesign may be described hereafter. In a number of variations, theintermediate gear 150 may include a first end 151 having a firstdiameter d6 which may include a plurality of gear teeth 152 located onthe first diameter d6. The intermediate gear 150 may also include asecond end 153 having a second diameter d7 and a plurality of gear teeth154 located on the second diameter d7. In a number of variations, thegear section on the second end 153 may be stepped inward from the gearsection on the first end 151.

In one illustration, the first end 151 of the intermediate gear 150 mayinclude a diameter d6 of approximately 14.03 mm and twenty-one gearteeth 152. In this illustration, the diameter d6 may be the contactdiameter for the gear teeth 152 on the intermediate gear 150 and thegear teeth 134 of the first ring gear 117. The first ring gear 117 mayhave fifty-three gear teeth 134. The intermediate gear 150 may also havea second end 153 which may have a second diameter d7 which may beapproximately 13.60 mm and may include twenty-one gear teeth 154. Inthis illustration, the second diameter d7 may be the contact diameterfor the gear teeth 154 on the intermediate gear 150 and the gear teeth135 of the second ring gear 128. The second ring gear 128 may havefifty-six gear teeth 135. The gear tooth geometry of the intermediategear 150 and the gear tooth geometry of the first and the second ringgears 117, 128 may be adjusted for the stepped intermediate gear designto achieve the desired contact diameters.

Referring to FIGS. 2, 5, 6, 12, and 15-17, in a number of variations, agear drive and actuator assembly 100 may include a return feature whichmay move the output shaft 121 in a known direction and position when anelectrical control signal or rotational force may be removed orinterrupted. In a number of variations, moving the electrical device 106or gear arrangement 116 in a known direction may allow the electricaldevice 106 or gear arrangement 116 to return to a known position whichmay prevent any number of conditions including, but not limited to, highengine boost pressure or exhaust emissions. In a number of variations, abias spring 156, 156 a may be used to provide the return feature. Thebias spring 156, 156 a may be located in various locations of the geardrive and actuator assemblies 100 and 100 a which may provide a desiredpackage size of the gear drive and actuator assemblies 100 and 100 a.

In one variation, a second ring gear 128 may have a radially extendingportion 155 which may be used to support a bias spring 156, a variationof which is illustrated in FIG. 6. In a number of variations, the biasspring 156 may be a helically wound spring having a first end 157, asecond end 158, and a plurality of coils 159 which may be spaced apart.In a number of variations, the first end 157 may be engaged in the firsthousing portion 102 so that movement of the first end 157 may beprevented. In a number of variations, the second end 158 may engage theextended portion 155 and may move with the extended portion 155 of thesecond ring gear 128 and the output shaft 121. At least a portion of theplurality of coils 159 may be located between the first ring gear 117and the second ring gear 128. In a number of variations, the pluralityof coils 159 may also surround the intermediate gear 129. In a number ofvariations, the bias spring 156 may be partially wound duringinstallation into the gear drive arrangement 116 to provide a residualtorque that may urge the extended portion 155, the second ring gear 128,and the output shaft 121 to rotate in a known direction. In onevariation, the bias spring 156 may be wound and installed into the geardrive arrangement 116 so that the residual torque may urge the outputshaft 121 to move in a first direction 148 towards an initial or knownposition. In a number of variations, there may be a physical stop in theactuator and gear drive assemblies 100, 100 a which may define a knownposition. In another variation, the known position may be determined byan externally controlled device including, but not limited to, aturbocharger mechanism, an exhaust gas recirculation valve, or anexhaust throttle valve.

In a number of variations, the ECU 109 may provide an electrical controlsignal which may have an electrical polarity that may cause theelectrical device 106 and the gear drive arrangement 116 to rotate theoutput shaft 121 in a second direction 149 which may be away from theinitial or known position. The rotation of the output shaft 121, thesecond ring gear 128, the extended portion 155, and the second end 158of the bias spring 156, may cause the bias spring 156 to store energy.The energy stored may be determined by the amount of rotation. In anumber of variations, when the ECU 109 may remove the electrical controlsignal from the electrical device 106, the energy stored in the biasspring 156 may then force the extended portion 155, the second ring gear128, and the output shaft 121 to rotate in a first direction 148 towardsthe initial or known position. The rotation may continue until the knownposition is reached.

In a number of variations, the electrical device 106 and the gear drivearrangement 116 may require approximately the same amount of torque asthe residual torque provided by the bias spring 156 so that theelectrical device 106 and the gear drive arrangement 116 may overcomethe residual torque and initiate movement of the shaft 121. The amountof residual torque provided by the bias spring 156 may also reduce thenet torque capability of the gear drive and actuator assembly 100. Thenet torque of a gear drive and actuator assembly 100 may be the torquethat may be available for controlling a device. In one illustration, ifthe gross torque capability of the gear drive and the actuator assembly100 may be 2.0 newton-meters (Nm) and the residual torque may be 0.5 Nm,the net torque capability of the gear drive and the actuator assembly100 may be 1.5 Nm.

In a number of variations, the residual torque may be set using thealignment and clocking features of the first housing portion 102 and thesecond housing portion 103 as previously described. During assembly ofthe first housing portion 102 and the second housing portion 103, thefirst cylindrical feature 140 may engage with the second housing portion103 and the second cylindrical feature 142 may engage with the firsthousing portion 102 at a first orientation point. At this firstorientation point, the bias spring 156 may apply a zero residual torqueto the output shaft 121. In a number of variations, rotation of one ofthe first or second housing portions 102, 103 about the central axis ofrotation 126 may cause an increase in the residual torque applied to theoutput shaft 121. The rotation of the first or second housing portion102, 103 may continue until the pin 144 in the second housing portion103 may engage with the mating hole 145 in the first housing portion102. At the point of engagement between the pin 144 and the mating hole145, the residual torque may be at the final predetermined value. In anumber of variations, the design of the bias spring 156 and the amountof rotation of the first housing portion 102 and the second housingportion 103 from the first orientation point to the point of engagementof the pin 144 in the second housing portion 103 and the mating hole 145in the first housing portion 102 may provide a suitable means foraccurately setting the residual torque on the output shaft 121.

In a number of variations, the bias spring 156 may also provide anadditional axial force for the end-play control of the output shaft 121.The end-play may be the range of axial movement of the output shaft 121along the central axis of rotation 126. In a number of variations, theplurality of bias spring coils 159 may be spaced apart in a manner whichmay act as a compression spring when installed in the gear drivearrangement 116. The bias spring 156 may be compressed between the firsthousing portion 102 and the extended portion 155 of the second ring gear128. In a number of variations, the installed height 160 of the biasspring 156 may be less than its initial height. In one illustration, theinitial wound height of bias spring 156 may be 25 mm and the installedheight 160 may be 20 mm. The 5 mm of compressed height of the biasspring 156 may provide an axial force which may bear against theextended portion 155 and may force the second ring gear 128 and theoutput shaft 121 in the first direction 161. In a number of variations,the output shaft 121 may include a stepped feature 162 which may contactthe second bearing 123 and may limit the axial movement of the outputshaft 121 in the first direction 161. In a number of variations, theaxial force provided by the bias spring 156 may also resist the axialmovement of the output shaft 121 in a second direction 163 therebylimiting endplay movement.

FIGS. 15-17, illustrate another variation including a bias springarrangement. In a number of variations, the construction and function ofthe gear drive and actuator arrangement 100 a may be similar to thatdescribed above and may be not be repeated.

In a number of variations, a gear drive and actuator arrangement 100 amay include an electrical device 106 a and a gear drive arrangement 116a located in a housing 101 a, a variation of which is illustrated inFIG. 17. The housing 101 a may include a first housing portion 102 a anda second housing portion 103 a. In a number of variations, a gear drivearrangement 116 a may comprise a first shaft 107 a and a central gear108 a which may be rotated by the electrical device 106 a in response toan electrical control signal from an ECU 109 a. The gear drivearrangement 116 a may further comprise a first ring gear 117 a, a secondring gear 128 a, and at least one intermediate gear 129 a. A first endof the intermediate gear 129 a may engage each of the first ring gear117 a and the central gear 108 a. A second end of the intermediate gear129 a may engage the second ring gear 128 a. In a number of variations,the second ring 128 a may be attached to the output shaft 121 a adjacenta second end 125 a of the output shaft 121 a. In a number of variations,a lever 127 a may be attached to a first end 124 a of the output shaft121 a. When a rotational force may be applied to the first shaft 107 a,the gear drive arrangement 116 b may cause the output shaft 121 a torotate.

Referring to FIGS. 6 and 17, in a number of variations, the extendedportion 155 of the second ring gear 128 may be removed and a modifiedbias spring 156 a may be moved to a location which may be coaxial withthe shaft 121 a and may be surrounding a portion of the shaft 121 a. Thesecond ring gear 128 a may be attached to, and rotatable with, theoutput shaft 121 a. In one variation, the removal of the extendedportion 155 of the second ring gear 128 and relocation of the biasspring 156 may allow the first and second housing portions 102 a and 103a to be a reduced size. In another variation, the second housing portion103 a may be increased in size in the area adjacent to the location ofthe bias spring 156 a while the first housing portion 102 a may bedecreased in size which may be favorable for certain applications.

In a number of variations, the bias spring 156 a may be a helicallywound spring having a first end 157 a, a second end 158 a, and aplurality of coils 159 a that may be spaced apart. The first end 157 amay be stationary and may engage the second housing portion 103 a. Thesecond end 158 a may be engaged with the second ring gear 128 a and maybe moveable with the second ring gear 128 a and the output shaft 121 a.At least a portion of the plurality of coils 159 a may surround aportion of the output shaft 121 a and a portion of the second ring gear128 a. In a number of variations, the bias spring 156 a may be partiallywound during installation into the gear drive arrangement 116 a so thatit may provide a residual torque that may urge the second ring gear 128a, and the output shaft 121 a to rotate in a known direction. In onevariation, the bias spring 156 a may be wound and installed into thegear drive arrangement 116 a and the residual torque may urge the outputshaft 121 a to move in a first direction 148 towards an initial or knownposition.

In a number of variations, the bias spring 156 a arrangement may includea return feature. In one variation, the ECU 109 a may provide anelectrical control signal which may have an electrical polarity that maycause the electrical device 106 b and the gear drive arrangement 116 bto rotate the output shaft 121 a in second direction 149 which may beaway from the initial or known position. The rotation of the outputshaft 121 a, the second ring gear 128 a, and the second end 158 a of thebias spring 156 a may cause the bias spring 156 a to store energy. Theenergy stored may be determined by the amount of rotation. When the ECU109 a may remove the electrical control signal from the electricaldevice 106 a, the energy stored in the bias spring 156 a may force thesecond ring gear 128 a and the output shaft 121 a to rotate in a firstdirection 148 towards the initial or known position. The rotation maycontinue until the known position may be reached.

In a number of variations, the bias spring 156 a arrangement may alsoprovide an end play control as previously described herein. Theplurality of bias spring coils 159 a may be spaced apart in a mannerwhich may act as a compression spring when installed in the gear drivearrangement 116 a. The bias spring 156 a may be compressed between thesecond housing portion 103 a and the second ring gear 128 a. In a numberof variations, the installed height 160 a of the bias spring 156 a maybe less than its initial height. In one illustration, the initial woundheight of the bias spring 156 a may be approximately 30 mm and theinstalled height 160 a may be approximately 25 mm. The 5 mm ofcompressed height, of the bias spring 156 a, may provide an axial forcethat may bear against the second ring gear 128 a and may force thesecond ring gear 128 a and the output shaft 121 a in the seconddirection 163. The output shaft 121 a may have a groove 164 which mayreceive a clip ring 165, a variation of which is illustrated in FIG. 17.The clip ring 165 may contact the second bearing 123 a and may limit thetravel of the output shaft 121 a in the second direction 163. The axialforce of the bias spring 156 a may also resist the movement of theoutput shaft 121 a in the first direction 161, however, the steppedfeature 162 a may also contact the second bearing 123 a and may limitthe axial movement of the output shaft 121 a in the first direction 161and may limit endplay movement.

In a number of variations, the gear drive and actuator assemblies 100,100 a illustrated above may provide optimized packaging for anapplication. The use of the planetary gear drive arrangements 116, 116 aillustrated above may allow for the actuator and gear drive arrangement100, 100 a to have a smaller length 166 and height 167 dimension, avariation of which is illustrated in FIG. 2, than the length 44 andheight 45 dimension of a typical actuator and gear drive arrangement 10which may include a gear drive arrangement 19 having a pinion gear 23and an intermediate gear 33, variations of which are illustrated inFIGS. 18 and 19, while producing the same or greater torque output. Inone variation, a typical actuator and gear drive arrangement 10 mayinclude a length dimension 44 of approximately 134 mm, while theactuator and gear drive arrangements 100, 100 a illustrated above mayinclude a length dimension 166 of approximately 110 mm. A reduced lengthmay be desirable for mounting the gear drive and actuator assembly 100,100 a to devices including, but not limited to, turbochargers, EGRvalves, exhaust throttle valve or other devices which may have limitedspace.

The following description of variants is only illustrative ofcomponents, elements, acts, products and methods considered to be withinthe scope of the invention and are not in any way intended to limit suchscope by what is specifically disclosed or not expressly set forth. Thecomponents, elements, acts, products and methods as described herein maybe combined and rearranged other than as expressly described herein andstill are considered to be within the scope of the invention.

Variation 1 may include a gear drive comprising: a housing; a first ringgear; a shaft supported in the housing, wherein the shaft has a centralaxis of rotation; a second ring gear, wherein the second ring gear iscoaxial with the shaft and operably connected and rotatable with theshaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end is operably engaged with the first ring gear and the secondend is operably engaged with the second ring gear; and a bias spring,wherein the bias spring comprises a first end, a second end, and aplurality of coils, and wherein the first end is stationary in thehousing.

Variation 2 may include a gear drive as set forth in Variation 1 whereinat least a portion of the bias spring is located between the first ringgear and the second ring gear and wherein the bias spring surrounds atleast a portion of the at least one intermediate gear.

Variation 3 may include a gear drive as set forth in any of Variations1-2 wherein the bias spring is located coaxial with the shaft and thesecond ring gear and wherein at least a portion of the plurality ofcoils surround a portion of the second ring gear.

Variation 4 may include a gear drive as set forth in any of Variations1-3 wherein the second end of the bias spring is operatively connectedto the shaft and moveable with the shaft, and wherein when a rotationalforce causes rotation of the shaft in a first direction away from aninitial position, the bias spring stores energy, and when the rotationalforce is removed, the stored energy from the bias spring causes theshaft to rotate in a second direction towards the initial position.

Variation 5 may include a gear drive as set forth in any of Variations1-4 wherein the second end of the bias spring is axially moveable withthe shaft and includes a first height and a second compressed height;wherein when the bias spring is installed into the housing, theplurality of coils are compressed to the second compressed height thatis less than the first height so that the plurality of coils storeenergy; and wherein the stored energy causes a force to be applied tothe shaft forcing it in a first axial direction and resisting movementof the shaft in a second axial direction.

Variation 6 may include a gear drive as set forth in any of Variations1-5 wherein the housing further comprises at least a first housingportion and a second housing portion wherein the first and the secondhousing portions include at least one alignment feature for aligning thefirst housing portion and the second housing portion and providing apredetermined residual torque.

Variation 7 may include a gear drive as set forth in Variation 6 whereinthe alignment feature comprises: a first cylindrical feature and a firstsurface on the first housing portion; a second cylindrical feature and asecond surface on the second housing portion; a pin attached to one ofthe first housing portion or the second housing portion; an opening onthe first housing portion or the second housing portion; wherein thefirst cylindrical feature on the first housing portion and the secondcylindrical feature on the second housing portion engage axially androtate until the first surface on the first housing portion and thesecond surface on the second housing portion come into contact so thatthe pin, on either the first housing portion or the second housingportion engages with the opening in either of the first housing portionor the second housing portion; wherein the first ring gear is located inthe first housing portion and the second ring gear and the shaft arelocated in the second housing portion, and wherein the first ring gearaligns coaxially with the second ring gear and the shaft; and whereinthe bias spring is wound to provide a predetermined residual torque tothe shaft.

Variation 8 may include a gear drive as set forth in any of Variations 1and 3-7 wherein the bias spring is located coaxial with the shaft andthe second ring gear and surrounds a portion of the shaft.

Variation 9 may include a gear drive as set forth in any of Variations1-8 further comprising: an actuator including an electrical device,wherein the electrical device is located in the housing and operablyconnected to the gear drive; and an electronic control unit, wherein theelectronic control unit is operably attached to the electrical device.

Variation 10 may include a gear drive as set forth in Variation 9wherein when the electronic control unit sends an electrical controlsignal to the electrical device to cause the electrical device and thegear drive to rotate the second ring gear, the shaft, and the second endof the bias spring in a second direction away from an initial positionwhich causes the bias spring to store energy and wherein when theelectronic control unit removes the electrical control signal to theelectrical device, the stored energy from the bias spring causes thesecond ring gear and the shaft to rotate in a first direction toward theinitial position.

Variation 11 may include a gear drive as set forth in any of Variations9-10 wherein at least one of the actuator, the electrical device, or thegear drive include a physical stop which defines the initial position.

Variation 12 may include a gear drive as set forth in any of Variations9-11 further comprising an externally controlled device, and wherein theexternally controlled device includes a stop which defines the initialposition.

Variation 13 may include a gear drive as set forth in Variation 12wherein the externally controlled device is one of a turbochargermechanism, an exhaust gas recirculation valve, or an exhaust throttlevalve.

Variation 14 may include a gear drive and actuator comprising: ahousing; an electrical device supported in the housing constructed andarranged to provide a rotational force in response to an electricalcontrol signal; a first shaft, wherein the first shaft is constructedand arranged to receive the rotational force from the electrical device;a central gear with a plurality of gear teeth, wherein the central gearis attached to the rotatable shaft and is rotatable with the shaft; afirst ring gear with a plurality of gear teeth; a second shaft supportedin the housing which has a central axis of rotation; a second ring gearwith a plurality of gear teeth, wherein the second ring gear is coaxialwith the second shaft and operably connected and rotatable with thesecond shaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end engages and contacts the central gear and the first ring gear,and wherein the second end engages and contacts the second ring gear; anintermediate gear plate, wherein the intermediate gear plate is coaxialwith the second ring gear and the second shaft; and a bias spring,wherein the bias spring includes a first end, a second end, and aplurality of coils, and wherein the first end is stationary in thehousing.

Variation 15 may include a gear drive and actuator as set forth inVariation 14 wherein when an electrical control signal is applied to theelectrical device it causes the electrical device and the gear drive torotate the second ring gear, the second shaft, and the second end of thebias spring in a second direction away from an initial position whichcauses the bias spring to store energy and wherein when the electroniccontrol unit removes the electrical control signal to the electricaldevice, the stored energy from the bias spring causes the second ringgear and the second shaft to rotate in a first direction toward theinitial position.

Variation 16 may include a gear drive and actuator as set forth inVariation 15 wherein at least one of the actuator, the electricaldevice, or the gear drive includes a physical stop which defines theinitial position.

Variation 17 may include a gear drive and actuator as set forth inVariation 15 further comprising an externally controlled device, whereinthe externally controlled device includes a stop which defines theinitial position.

Variation 18 may include a gear drive and actuator as set forth inVariation 17 wherein the externally controlled device is one of aturbocharger mechanism, an exhaust gas recirculation valve, or anexhaust throttle valve.

Variation 19 may include a gear drive and actuator as set forth in anyof Variations 15-18 wherein the second end of the bias spring is axiallymoveable with the second shaft and includes a first height and a secondcompressed height; wherein when the bias spring is installed into thehousing, the plurality of coils are compressed to the second compressedheight that is less than the first height so that the plurality of coilsstore energy; and wherein the stored energy causes a force to be appliedto the second shaft forcing it in a first axial direction and resistingmovement of the second shaft in a second axial direction.

Variation 20 may include a gear drive and actuator as set forth in anyof Variations 15-19 wherein the housing further comprises at least afirst housing portion and a second housing portion wherein the first andsecond housing portions include at least one alignment feature foraligning the first housing portion and the second housing portion andproviding a predetermined residual torque.

The above description of select variations within the scope of theinvention is merely illustrative in nature and, thus, variations orvariants thereof are not to be regarded as a departure from the spiritand scope of the invention.

What is claimed is:
 1. A gear drive comprising: a housing; a first ringgear; a shaft supported in the housing, wherein the shaft has a centralaxis of rotation; a second ring gear, wherein the second ring gear iscoaxial with the shaft and operably connected and rotatable with theshaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end is operably engaged with the first ring gear and the secondend is operably engaged with the second ring gear; and a bias spring,wherein the bias spring comprises a first end, a second end, and aplurality of coils, wherein the first end is stationary in the housing,and wherein at least a portion of the bias spring is located between thefirst ring gear and the second ring gear and surrounds at least aportion of the at least one intermediate gear.
 2. The gear drive ofclaim 1 wherein the second end of the bias spring is operativelyconnected to the shaft and moveable with the shaft, and wherein when arotational force causes rotation of the shaft in a first direction awayfrom an initial position, the bias spring stores energy, and when therotational force is removed, the stored energy from the bias springcauses the shaft to rotate in a second direction towards the initialposition.
 3. The gear drive of claim 1 wherein the second end of thebias spring is axially moveable with the shaft and includes a firstheight and a second compressed height; wherein when the bias spring isinstalled into the housing, the plurality of coils are compressed to thesecond compressed height that is less than the first height so that theplurality of coils store energy; and wherein the stored energy causes aforce to be applied to the shaft forcing it in a first axial directionand resisting movement of the shaft in a second axial direction.
 4. Thegear drive of claim 1 wherein the housing further comprises at least afirst housing portion and a second housing portion wherein the first andthe second housing portions include at least one alignment feature foraligning the first housing portion and the second housing portion andproviding a predetermined residual torque.
 5. The gear drive of claim 4wherein the alignment feature comprises: a first cylindrical feature anda first surface on the first housing portion; a second cylindricalfeature and a second surface on the second housing portion; a pinattached to one of the first housing portion or the second housingportion; an opening on the first housing portion or the second housingportion; wherein the first cylindrical feature on the first housingportion and the second cylindrical feature on the second housing portionengage axially and rotate until the first surface on the first housingportion and the second surface on the second housing portion come intocontact so that the pin, on either the first housing portion or thesecond housing portion, engages with the opening in either of the firsthousing portion or the second housing portion; wherein the first ringgear is located in the first housing portion and the second ring gearand the shaft are located in the second housing portion, and wherein thefirst ring gear aligns coaxially with the second ring gear and theshaft; and wherein the bias spring is wound to provide a predeterminedresidual torque to the shaft.
 6. The gear drive of claim 1 furthercomprising: an actuator including an electrical device, wherein theelectrical device is located in the housing and operably connected tothe gear drive; and an electronic control unit, wherein the electroniccontrol unit is operably attached to the electrical device.
 7. The geardrive of claim 6 wherein when the electronic control unit sends anelectrical control signal to the electrical device to cause theelectrical device and the gear drive to rotate the second ring gear, theshaft, and the second end of the bias spring in a second direction awayfrom an initial position which causes the bias spring to store energyand wherein when the electronic control unit removes the electricalcontrol signal to the electrical device, the stored energy from the biasspring causes the second ring gear and the shaft to rotate in a firstdirection toward the initial position.
 8. The gear drive of claim 6wherein at least one of the actuator, the electrical device, or the geardrive include a physical stop which defines the initial position.
 9. Thegear drive of claim 6 further comprising an externally controlleddevice, and wherein the externally controlled device includes a stopwhich defines the initial position.
 10. The gear drive of claim 9wherein the externally controlled device is one of a turbochargermechanism, an exhaust gas recirculation valve, or an exhaust throttlevalve.
 11. A gear drive and actuator comprising: a housing; anelectrical device supported in the housing constructed and arranged toprovide a rotational force in response to an electrical control signal;a first shaft, wherein the first shaft is constructed and arranged toreceive the rotational force from the electrical device; a central gearwith a plurality of gear teeth, wherein the central gear is attached tothe rotatable shaft and is rotatable with the shaft; a first ring gearwith a plurality of gear teeth; a second shaft supported in the housingwhich has a central axis of rotation; a second ring gear with aplurality of gear teeth, wherein the second ring gear is coaxial withthe second shaft and operably connected and rotatable with the secondshaft; at least one intermediate gear, wherein the at least oneintermediate gear includes a first end and a second end, wherein thefirst end engages and contacts the central gear and the first ring gear,and wherein the second end engages and contacts the second ring gear; anintermediate gear plate, wherein the intermediate gear plate is coaxialwith the second ring gear and the second shaft; and a bias spring,wherein the bias spring includes a first end, a second end, and aplurality of coils, and wherein the first end is stationary in thehousing.
 12. The gear drive and actuator of claim 11 wherein when anelectrical control signal is applied to the electrical device it causesthe electrical device and the gear drive to rotate the second ring gear,the second shaft, and the second end of the bias spring in a seconddirection away from an initial position which causes the bias spring tostore energy and wherein when the electronic control unit removes theelectrical control signal to the electrical device, the stored energyfrom the bias spring causes the second ring gear and the second shaft torotate in a first direction toward the initial position.
 13. The geardrive and actuator of claim 12 wherein at least one of the actuator, theelectrical device, or the gear drive includes a physical stop whichdefines the initial position.
 14. The gear drive and actuator of claim12 further comprising an externally controlled device, wherein theexternally controlled device includes a stop which defines the initialposition.
 15. The gear drive and actuator of claim 14 wherein theexternally controlled device is one of a turbocharger mechanism, anexhaust gas recirculation valve, or an exhaust throttle valve.
 16. Thegear drive and actuator of claim 11 wherein the second end of the biasspring is axially moveable with the second shaft and includes a firstheight and a second compressed height; wherein when the bias spring isinstalled into the housing, the plurality of coils are compressed to thesecond compressed height that is less than the first height so that theplurality of coils store energy; and wherein the stored energy causes aforce to be applied to the second shaft forcing it in a first axialdirection and resisting movement of the second shaft in a second axialdirection.
 17. The gear drive of claim 11 wherein the housing furthercomprises at least a first housing portion and a second housing portionwherein the first and second housing portions include at least onealignment feature for aligning the first housing portion and the secondhousing portion and providing a predetermined residual torque.
 18. Agear drive comprising: a housing; a first ring gear; a shaft supportedin the housing, wherein the shaft has a central axis of rotation; asecond ring gear, wherein the second ring gear is coaxial with the shaftand operably connected and rotatable with the shaft; at least oneintermediate gear, wherein the at least one intermediate gear includes afirst end and a second end, wherein the first end is operably engagedwith the first ring gear and the second end is operably engaged with thesecond ring gear; and a bias spring, wherein the bias spring comprises afirst end, a second end, and a plurality of coils, wherein the first endis stationary in the housing, and wherein the bias spring is locatedcoaxial with the shaft and the second ring gear and surrounds a portionof the shaft.
 19. A gear drive comprising: a housing; a first ring gear;a shaft supported in the housing, wherein the shaft has a central axisof rotation; a second ring gear, wherein the second ring gear is coaxialwith the shaft and operably connected and rotatable with the shaft; atleast one intermediate gear, wherein the at least one intermediate gearincludes a first end and a second end, wherein the first end is operablyengaged with the first ring gear and the second end is operably engagedwith the second ring gear; and a bias spring, wherein the bias springcomprises a first end, a second end, and a plurality of coils, whereinthe first end is stationary in the housing, and wherein the bias springis located coaxial with the shaft and the second ring gear and whereinat least a portion of the plurality of coils surround a portion of thesecond ring gear.